The development of the DVD followed the development of CD ROM in an effort to achieve sufficient storage capacity for large video files to enable a single disc could carry a full length motion picture, albeit compressed using a compression technique such as the Moving Picture Expert Group compression (MPEG) technique. Since its first introduction in the mid 1990's, the DVD has proliferated, becoming the preferred medium of choice for wide scale distribution of motion picture and video content to consumers.
Present day DVDs typically include at least one, and usually several A/V/streams in parallel synchronism to each other. Often such A/V streams comprise different recordings of the same scene shot from a different angle. Hence, such different A/V streams are often referred to as “angles”. Selection of different angles (i.e., different streams) occurs through a process known as “multi-angle navigation” whereby a viewer selects a desired angle by selecting an associated icon on a display screen. The DVD specification adopted by the manufacturers of DVDs and associated playback devices defines a process known as “multi-angle video” whereby a content author can define as many as nine concurrent A/V streams, any one of which can appear on a display screen at any time. During playback, the viewer can switch seamlessly among a set of synchronized A/V streams by actuating a command via a button on a DVD player or on the remote control device for such player. However, under known implementations of currently available DVD authoring software, the button highlight information (HLI) stored in each A/V stream always remains identical to that in other streams.
As a result a given button will appear in the same way and in the same location to enable execution of the same command no matter what angle appears on the display screen. Additional HLI properties will also be the same, such as instructions for directional navigation between buttons and button color schemes. Sub-picture and audio data stored in each A/V stream also remains identical. Such Sub-picture data describes the rendering of buttons, subtitles, and other graphical elements displayed over video.
Thus, there exists a need for multi-angle DVD navigation technique that affords the content author an ability to both assign contextually dependent interactivity and to substitute differing audio and sub-picture data into parallel, synchronized Audio/Visual (A/V) streams playing from a DVD.